This invention aims at the improvement of metering valves, lubrication systems using such valves and oleodynamic plants in general, that is to say it deals with a metering valve and advantageous modifications in the members of automatic and semi-automatic cycle lubrication systems for motive machines, machine tools and power consuming machines for industrial and agricultural applications, particularly in case of earth moving machines and crawlers in general, subject to projection of stones and to be used below ground level or for grading. The improvements also have utility in oleodynamic plants and systems in general. The state of art prior to this invention is distinguished by centralized lubrication systems equipped with only a single distribution tube, from which single outputs are branched; each out-put being equipped with a metering valve at its end of such a type as is disclosed in U.S. Pat. No. 4,016,897 of Zeo Asioli, presenting an outer body formed by a housing with an intermediate prismatic band, for screwing operation and with two threaded end parts, one for the screwing to the delivery fitting or to the distributor body, the other for the direct screwing to the member to be lubricated (pivot, bushing, box and the like) or for the screwing into another pipe-fitting, being part of a distribution tube of the already proportioned oil.
This prior state of art presents some shortcomings and inconveniences because of the fact that such metering valves, the casing of which must necessarily be produced with machine tools, are very expensive and present a considerable weakening in the two threaded areas so that they are frequently subject to breaking due to shocks (facilitated by their excessive projection) or vibrations or projection of stones because of the effect of the action of the wheels of the vehicle. Consequently, in machines like such as excavators for instance the lubrication is still effected by lubricant injection by hand using grease guns in order to avoid the frequent breakage of the metering valves equipped with threads and considerably projecting from the body of the associated machine; this causes a considerable loss of time and damage to the machine, which, in this way, is lubricated in a desultory manner. Moreover, because the distributors for more than one derivation, which have been heretofore constructed as one body only, on which all necessary threadings are made, in case of damage to a single threading only, the whole distributor body has to be discarded, which means a considerable cost and damage. Finally, the possible theorical direct insertion of the metering valve members into a gauged bore of more than one diameter for the coupling in this bore, practically is not feasable because of the high cost of the precision operations necessary to obtain the bore.